Investigation into West explosion continues

Updated 11:50 am, Friday, April 26, 2013

Workers pause for a memorial service at the site of the fire and explosion in West, Texas on April 24 2013.

Workers pause for a memorial service at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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An officer sounds taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

An officer sounds taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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An ATF agent unveils flags for during a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

An ATF agent unveils flags for during a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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A forensic mapper works at the crater at the site of the fire and explosion in West, Texas on April 24 2013.

A forensic mapper works at the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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A forensic mapper works measuring the crater at the site of the fire and explosion in West, Texas on April 24 2013.

A forensic mapper works measuring the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Forensic mappers work at the site of the fire and explosion in West, Texas on April 24 2013.

Forensic mappers work at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Brian Hoback with ATF explains details to Kelly Kistner , assistant state fire marshall, and Robert Champion, ATF at the site of the fire and explosion in West, Texas on April 24 2013.

Brian Hoback with ATF explains details to Kelly Kistner , assistant state fire marshall, and Robert Champion, ATF at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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The crater measures 93 feet across by 10 feet deep at the site of the fire and explosion in West, Texas on April 24 2013.

The crater measures 93 feet across by 10 feet deep at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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the site of the fire and explosion in West, Texas on April 24 2013.

the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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An ATF investigator descends into the crater — 93 feet wide and 10 feet deep — at the site of the April 17 explosion in West.

An ATF investigator descends into the crater — 93 feet wide and 10 feet deep — at the site of the April 17 explosion in West.

Photo: Photos By Tom Reel / San Antonio Express-News

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Agents walk in the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Agents walk in the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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the site of the fire and explosion in West, Texas on April 24 2013.

the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Forensic mappers work the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Forensic mappers work the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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A first responder fire truck rests damaged at the site of the fire and explosion in West, Texas on April 24 2013.

A first responder fire truck rests damaged at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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A ten foot crater remains at the site of the fire and explosion in West, Texas on April 24 2013.

A ten foot crater remains at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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A ten foot deep hole remains at the site of the fire and explosion in West, Texas on April 24 2013.

A ten foot deep hole remains at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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A forensic mapper climbs over the edge of the crater at the site of the fire and explosion in West, Texas on April 24 2013.

A forensic mapper climbs over the edge of the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Forensic mappers measure the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Forensic mappers measure the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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ATF agents search the bank of the rail tracks for evidence at the site of the fire and explosion in West, Texas on April 24 2013.

ATF agents search the bank of the rail tracks for evidence at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Belongings are lined up outside the apartment complex adjacent to the the site of the fire and explosion in West, Texas on April 24 2013.

Belongings are lined up outside the apartment complex adjacent to the the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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the site of the fire and explosion in West, Texas on April 24 2013.

the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Family pictures rest outside the apartment complex at the site of the fire and explosion in West, Texas on April 24 2013.

Family pictures rest outside the apartment complex at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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the site of the fire and explosion in West, Texas on April 24 2013.

the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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ATF agent Robert Champion and Assistant State Fire Marshal Kelly Kistner are two of the lead investigators on the disaster.

ATF agent Robert Champion and Assistant State Fire Marshal Kelly Kistner are two of the lead investigators on the disaster.

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A Stetson hat rests outside the apartment complex adjacent to the site of the fire and explosion in West, Texas on April 24 2013.

A Stetson hat rests outside the apartment complex adjacent to the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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the site of the fire and explosion in West, Texas on April 24 2013.

the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL, San Antonio Express-News

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Forensic mappers work the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Forensic mappers work the crater at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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An adjacent lot where a children's playground existed stands in rubble at the site of the fire and explosion in West, Texas on April 24 2013.

An adjacent lot where a children's playground existed stands in rubble at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Workers stand at attention during taps at the site of the fire and explosion in West, Texas on April 24 2013.

Workers stand at attention during taps at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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An officer plays taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

An officer plays taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: TOM REEL

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Trees nearby are ruined at the site of the fire and explosion in West, Texas on April 24 2013.

Trees nearby are ruined at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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Trees in nearby yards were knocked down at the site of the fire and explosion in West, Texas on April 24 2013.

Trees in nearby yards were knocked down at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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Officials display before and after photos of the site of the fire and explosion in West, Texas on April 24 2013.

Officials display before and after photos of the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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An intact rail car is covered by plastic to prevent water absorption at the site of the fire and explosion in West, Texas on April 24 2013.

An intact rail car is covered by plastic to prevent water absorption at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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An officer plays taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

An officer plays taps at a memorial ceremony at the site of the fire and explosion in West, Texas on April 24 2013.

Photo: For The San Antonio Express-News

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Investigation into West explosion continues

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WEST — Investigators remained here in full force Friday, continuing to sift through the destruction caused by a deadly fertilizer plant explosion last week.

A cause of the blast has not yet been determined, State Fire Marshal's Office spokeswoman Rachel Moreno said Friday. A crew of 70 remains at the scene with no immediate plans of wrapping up the investigation, she said.

Meanwhile, city officials have informed some residents in Zone 3, the hardest hit area of the explosion, that they might be able to begin sifting through what remains of their properties as early as Saturday.

Fifteen people — the majority of whom where first responders — died in the April 17 disaster. President Barack Obama, Gov. Rick Perry and Sen. John Cornyn were among the dignitaries who expressed condolences and pledged support Thursday at a massive memorial service on the Baylor University campus.